在 ASP.NET MVC 中创建 ETag 过滤器 [英] Create ETag filter in ASP.NET MVC

问题描述

我想在 MVC 中创建一个 ETag 过滤器.问题是我无法控制 Response.OutputStream，如果我能够做到，我将根据结果流简单地计算 ETag.我之前在 WCF 中做过这件事，但在 MVC 中找不到任何简单的想法.

I would like to create an ETag filter in MVC. The problem is that I can't control the Response.OutputStream, if I was able to do that I would simply calculate the ETag according to the result stream. I did this thing before in WCF but couldn't find any simple idea to do that in MVC.

我希望能够写出这样的东西

I want to be able to write something like that

[ETag]
public ActionResult MyAction()
{
    var myModel = Factory.CreateModel();
    return View(myModel);
}

有什么想法吗?

推荐答案

非常感谢，这正是我想要的.刚刚对 ETagFilter 做了一个小的修复，如果内容没有改变，它将处理 304

Thanks a lot it is exactly what I was looking for. Just made a small fix to the ETagFilter that will handle 304 in case that the content wasn't changed

public class ETagAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        filterContext.HttpContext.Response.Filter = new ETagFilter(filterContext.HttpContext.Response, filterContext.RequestContext.HttpContext.Request);
    }
}

public class ETagFilter : MemoryStream
{
    private HttpResponseBase _response = null;
    private HttpRequestBase _request;
    private Stream _filter = null;

    public ETagFilter(HttpResponseBase response, HttpRequestBase request)
    {
        _response = response;
        _request = request;
        _filter = response.Filter;
    }

    private string GetToken(Stream stream)
    {
        byte[] checksum = new byte[0];
        checksum = MD5.Create().ComputeHash(stream);
        return Convert.ToBase64String(checksum, 0, checksum.Length);
    }

    public override void Write(byte[] buffer, int offset, int count)
    {
        byte[] data = new byte[count];
        Buffer.BlockCopy(buffer, offset, data, 0, count);
        var token = GetToken(new MemoryStream(data));

        string clientToken = _request.Headers["If-None-Match"];

        if (token != clientToken)
        {
            _response.Headers["ETag"] = token;
            _filter.Write(data, 0, count);
        }
        else
        {
            _response.SuppressContent = true;
            _response.StatusCode = 304;
            _response.StatusDescription = "Not Modified";
            _response.Headers["Content-Length"] = "0";
        }
    }
}

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